The present disclosure relates generally to seismic exploration and specifically to structure tensor constrained tomographic velocity analysis.
Seismology is used for exploration, archaeological studies, and engineering projects that require geological information. Exploration seismology provides data that, when used in conjunction with other available geophysical, borehole, and geological data, can provide information about the structure and distribution of rock types and their contents. Such information greatly aids searches for water, geothermal reservoirs, and mineral deposits such as hydrocarbons and ores. Most oil companies rely on exploration seismology to select sites in which to drill exploratory oil wells.
Traditional seismology employs artificially generated seismic waves to map subsurface structures. The seismic waves propagate from a source down into the earth and reflect from boundaries between subsurface structures. Surface receivers detect and record reflected seismic waves for later analysis. Though some large-scale structures can often be perceived from a direct examination of the recorded signals, the recorded signals are typically processed using a subsurface velocity model to remove distortion and reveal finer detail in the subsurface image. The quality of the subsurface image may depend on the accuracy of the subsurface velocity model.
Velocity analysis may include extracting velocity information from seismic data. One process for velocity analysis includes an advanced prestack depth migration technique, which has become an attractive tool for velocity analysis, not only because of its sensitivity to the velocity model but also its ability to generate residual errors in the post-migration domain. A popular approach to the migration-velocity analysis (MVA) is the residual-curvature analysis on a common image point gather, which is based on residual moveout to measure velocity error. Residual-curvature analysis in areas of complex structure is a coupled migration-inversion problem that can be analyzed from a tomographic perspective.
Existing tomographic MVA processing methods require the step of picking, including (1) horizon picking in the depth image volume for the estimation of local dip and azimuth information and (2) residual moveout picking in the depth-migrated common image gathers for the measurement of depth residual information. Manual picking may be tedious and time-consuming, particularly in iterative processing and interpretation techniques.
While embodiments of this disclosure have been depicted and described and are defined by reference to exemplary embodiments of the disclosure, such references do not imply a limitation on the disclosure, and no such limitation is to be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and not exhaustive of the scope of the disclosure.